System level function based access control for smart contract execution on a blockchain

ABSTRACT

Technologies are shown for system level function based access control for smart contract execution on a blockchain. Access control rules control function calls at a system level by utilizing function boundary detection instrumentation in a kernel that executes smart contracts. The detection instrumentation generates a call stack that represents a chain of function calls in the kernel for execution of a smart contract. The access control rules are applied to the function call stack to allow or prohibit specific functions or function call chains. Access control rules can also define allowed or prohibited parameter data in the function call chain. If the function call chain or parameters do not meet the requirements defined in the access control rules, then the function call can be blocked from executing or completing execution. The access control rules can produce sophisticated access control policies based on complex function call chains.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Appl. No.62/774,799 for “INTEGRATION OF FUNCTION BASED ACCESS CONTROL, DATA BASEDACCESS CONTROL, AND INSTRUMENTATION FRAMEWORKS TO BLOCKCHAIN DATASTRUCTURES” filed Dec. 3, 2018, herein incorporated by reference in itsentirety for all purposes.

BACKGROUND

Blockchains generally provide decentralized distributed ledgers tosecurely and immutably record transactions and other data. Currently,there are several approaches to maintaining security in blockchains.

One aspect of blockchain security is obtained by Proof of Work, whichare typically cryptographic puzzles with dynamic levels of difficulty.Proof of Work generally ensures that it is computationally infeasiblefor a single party to rewrite the blockchain with its own entries. Forpublic blockchains, this also allows a winning node to be selected thatcan append a new transaction block to a blockchain.

Another aspect of blockchain security is the use of consensus protocolsthat act as gatekeepers to authorize a “miner” to write to theblockchain. These protocols are typically of two types: 1) cryptographiccomputational with very low collision probability to ensure that onlyone writer wins within a time period; and 2) non-cryptographicprotocols, such as Proof of elapsed Time (PoET), Asynchronous ByzantineFault Tolerance (aBFT), Practical Byzantine Fault Tolerance (pBFT), orHashgraph augmented parallel consensus protocols.

Yet another aspect of blockchain security is the use of private keys byall blockchain actors, e.g. users, contracts, signers/validators/miners.Each of these entities protect their private keys assiduously in asoftware or hardware framework, such as digital wallet systems likeMETAMASK, TREZOR, or the LEDGER NANO series.

However, none of the security approaches above serves effectively assecurity gatekeepers for the operations of the blockchain platformitself or for smart contracts deployed on the blockchain. If ablockchain is coded with doorways (either inadvertently, by design, ordue to bugs), or if the execution environment that the blockchainplatform provides to run smart contracts is compromised, then ablockchain may be vulnerable to security breaches. As a consequence,smart contracts on some blockchains have been hacked and funds stolen.

For example, the ETHEREUM blockchain supported a fallback function forsmart contracts that was always executed at the end of the smartcontract. This fallback function was exploited by hackers to drainwallets by inserting a Deposit( ) call from the smart contract walletinto a wallet controlled by the hackers.

It is with respect to these and other considerations that the disclosuremade herein is presented.

SUMMARY

Technologies are disclosed for system level function based accesscontrol for smart contract execution on a blockchain.

Examples of the disclosed technology concern methods, systems and mediafor system level function based access control for smart contractexecution on a blockchain, in a kernel execution framework for smartcontract execution on a blockchain, where the kernel execution frameworkis configured to perform function boundary detection involve detecting afunction call by one or more methods of a smart contract on theblockchain, adding the function call to a function call stack for thesmart contract; checking the function call stack against a set offunction based access control rules that defines one or more permittedor prohibited sequences of function calls, and, if the function callstack includes one or more function calls that are not permitted underthe set of function based access control rules, then blocking executionor completion of the function call.

In certain examples, the function call stack includes each functioncalled during execution of the smart contract, the set of function basedaccess control rules includes at least one access control rule thatdefines a sequence of function calls, and the step of checking thefunction call stack against the set of function based access controlrules includes checking the function call stack against the sequence offunction calls defined in the access control rule that defines asequence of function calls.

In certain other examples, the set of function based access controlrules includes at least one data based access control rule and the stepof detecting a function call by one or more methods of a smart contracton the blockchain includes detecting at least one value included in thefunction call stack. The step of checking the function call stackagainst a set of function based access control rules involves checkingthe value included in the function call stack against the data basedaccess control rule. The step of blocking the function call if thesequence of function calls is not permitted under the set of functionbased access control rules includes blocking the function call if thevalue included in the sequence of function calls is not permitted underthe set of data based access control rules.

In particular examples, the set of function based access control rulesis stored on a blockchain and the method includes modifying the set offunction based access control rules by adding a function based accesscontrol rule block to the blockchain.

In still other examples, the kernel execution framework is a Linuxoperating system framework and the function boundary detection comprisesextended Berkeley Packet Filtering. In certain examples, the set offunction based access control rules includes at least one of a whitelist of allowed sequences of function calls and a black list ofprohibited sequences of function calls.

In yet another example, the steps of detecting a function call by one ormore methods of a smart contract on the blockchain, adding the functioncall to a function call stack for the smart contract, checking thefunction call stack against the set of function based access controlrules, and blocking the function if the function call is not permittedunder the set of function based access control rules are performedwithin a virtual machine executing the framework for execution of thesmart contract on the blockchain.

It should be appreciated that the above-described subject matter mayalso be implemented as a computer-controlled apparatus, a computerprocess, a computing system, or as an article of manufacture such as acomputer-readable medium. These and various other features will beapparent from a reading of the following Detailed Description and areview of the associated drawings. This Summary is provided to introducea selection of concepts in a simplified form that are further describedbelow in the Detailed Description.

This Summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended that thisSummary be used to limit the scope of the claimed subject matter.Furthermore, the claimed subject matter is not limited toimplementations that solve any or all disadvantages noted in any part ofthis disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The Detailed Description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Thesame reference numbers in different figures indicate similar oridentical items.

FIG. 1 is an architectural diagram showing an illustrative example of asystem for a storing transaction data using a blockchain and storingaccess control rules using a blockchain;

FIG. 2A is a data architecture diagram showing an illustrative exampleof a transaction data blockchain securing transaction data;

FIG. 2B is a data architecture diagram showing an illustrative exampleof a transaction data block securing transaction data that includesmethods that are executed by a blockchain platform;

FIG. 3A is a functional block diagram showing an illustrative example ofa blockchain platform with virtual machines that execute methods from atransaction data block in a kernel instrumented with function boundaryaccess control in accordance with the disclosed technology;

FIG. 3B is a data architecture diagram showing illustrative examples offunction or data based access control rules in accordance with thedisclosed technology;

FIG. 4A is a control flow diagram showing an illustrative example of aprocess for defining sets of function or data based access control rulesin accordance with the disclosed technology;

FIG. 4B is a control flow diagram showing an illustrative example of aprocess in accordance with the disclosed technology for applyingfunction or data based access control rules to function calls in a callstack in a kernel instrumented with function boundary access control;

FIG. 4C is a control flow diagram illustrating an example of avalidation process for blocks added to the transaction data blockchainor access control policy blockchain distributed to untrusted nodes;

FIG. 5 is a data architecture diagram showing an illustrative example ofa user using an application programming interface to invoke methods in adata block on the transaction data blockchain;

FIG. 6A is a data architecture diagram illustrating a simplified exampleof a blockchain ledger based on the transaction data blocks of thetransaction data blockchain or access control rule blocks of the accesscontrol policy blockchain of FIG. 1;

FIG. 6B is a data architecture diagram showing an illustrative exampleof smart contract code, transactions and messages that are bundled intoa block so that their integrity is cryptographically secure and so thatthey may be appended to a blockchain ledger;

FIG. 7 is a computer architecture diagram illustrating an illustrativecomputer hardware and software architecture for a computing systemcapable of implementing aspects of the techniques and technologiespresented herein;

FIG. 8 is a diagram illustrating a distributed computing environmentcapable of implementing aspects of the techniques and technologiespresented herein; and

FIG. 9 is a computer architecture diagram illustrating a computingdevice architecture for a computing device capable of implementingaspects of the techniques and technologies presented herein.

DETAILED DESCRIPTION

In the context of blockchain security, it can be advantageous to utilizefunction based access control (FBAC) in accordance with the disclosedtechnology to improve the security of blockchain operations on ablockchain platform.

A security framework utilizing FBAC in accordance with the disclosedtechnology can operate at a function call level in a kernel executingblockchain methods on the blockchain platform to significantly improvethe security of blockchains at a system level in addition to thecryptographic and consensus security approaches typically utilized inblockchains.

One technical advantage of certain aspects of the system level securityof the disclosed technology is that smart contracts or blocks alreadydeployed to a blockchain, and which are, therefore, immutable, can beprotected without editing or redeploying the smart contracts or blocks.Because the disclosed technology provides security at the system level,it can be highly extensible and easily configurable.

Another technical advantage of certain aspects of the disclosedtechnology is that function and data based access control rules can bedirected to checking chains of function calls in a call stack instead ofbeing limited to checking a single function call.

The access control rules themselves can also be stored on a blockchainand secured by the multi-signature cryptographic and consensus securityapproaches utilized by the blockchain. Storing access control rules on ablockchain permits the rules to be audited and traced to their origin.Updates to the access control rules can also be stored on the blockchainand the disclosed technology can be configured to obtain the most recentrules for use in the FBAC security framework.

Because the access control rules are generally static data rather thanexecutable code, the rules themselves are highly resistant toexploitation. By contrast, executable code in smart contracts or blockscan be vulnerable to exploits in an underlying virtual machine (VM) thatexecutes the smart contract code.

The access control rules can be realized in some implementations by anaddendum to the VM in a blockchain platform that executes smartcontracts. In other implementations, the access control rules are readin from a blockchain to a standalone privileged system level module.

In general, the FBAC framework of the disclosed technology can preventinvocation of specific smart contracts, specific smart contract functionchains, and blockchain infrastructure functions. The FBAC frameworkmakes it possible to define roles and bindings at various levels, suchas functions, contracts, channels, or consensus algorithms. The FBACframework may be used in some instances to sandbox algorithms that areused in a blockchain platform, which can help ensure uniformity ofconfiguration, for example, among nodes with different consensusalgorithms.

In general terms, the FBAC framework of the disclosed technologyutilizes function boundary detection instrumentation in a kernel of ablockchain platform. The function boundary detection instrumentation cantrace when a function has been entered and exited in the kernel. Oneexample of function boundary detection instrumentation is the BerkeleyPacket Filter (eBPF) framework in the LINUX operating system.

The FBAC framework of the disclosed technology can, in someimplementations, utilize system level support to run. For example, inone embodiment, the FBAC framework may run in its own privileged VM thatruns the FBAC and can exercise control over the VMs that run smartcontracts. In another embodiment however, the same VM can run both smartcontracts and the FBAC. The VM may also use an underlying operatingsystem's function boundary detection instrumentation support, e.g. eBPF.

Multiple FBAC policies can be associated, or pivoted, with multipleentities. For example, a wallet address on a blockchain for financialtransactional entries may be associated. For enterprise transactions,this pivot can be specified as a field within each FBAC policy. Afterstoring an FBAC policy in a blockchain, each peer, validator, ortransaction initiator in the blockchain may have a uniform view of thepolicies.

As noted above, the access control rules can be both function and databased. Data passed as function parameters can be monitored to controlaccess based on the parameters. The data based access control rules canbe stored in a blockchain. Data based access control rules can be used,for example, to shield certain data sections of a blockchain fromgeneral access. For example, in a permissioned blockchain, marker orkeys can be utilized to determine access to data.

As discussed above, hackers were able to exploit a fallback function ina smart contract by inserting a Deposit( ) call that directed funds in acompromised wallet to a wallet controlled by the hackers. In oneexample, the disclosed technology can be used to prevent such an exploitusing an access control rule that prohibits a Deposit( ) call at the endof a chain of function calls.

Another example of a possible use of the disclosed technology ispermissioned blockchains. Current blockchain platforms achieve differentpermissioned views for different participants by segregating themessaging and access to data across channels. However, some smartcontracts may end up being shared across hundreds of entities. Thedisclosed technology may be applied to define access control rules thatdetermine the functions that different users, e.g. user, user admin,group admin, cluster admin, logical grouping admin.

Yet another example of a possible use of the disclosed technology is toprovide Quality of Service (QoS) in a blockchain platform. The disclosedtechnology can be utilized to apply access control rules to implementdifferential resource allocation on a highly granular level to deliver adesired QoS for a particular entity or functionality.

Still another example of a possible use of the disclosed technology isresource or rate limit enforcement. Function chains that are invoked canbe identified through the framework, their resource utilizationconstantly updated, and based on that, or, based on a fixed count pertime period, access control rules applied to enforce resource or ratelimits.

Another example of a possible use of the disclosed technology is toimplement circuit breakers. For example, when a smart contractmalfunctions because of underlying bugs or similar issues, or due toexternal failures, such as networking I/O issues or similar, it willerror out. If a particular function chain is repeatedly invoked, and itis known to be failing constantly, then a circuit breaker can be useful.Access control rules are applied to implement a circuit breaker functionin this context by preventing further invocation of the function chainuntil a prescribed/preset time has elapsed. This may be especiallyuseful in preventing a blockchain platform from getting overwhelmed. Ina larger distributed systems context, at scale, this may help achieveoptimal blockchain request routing.

One other example of a possible use of the disclosed technology is toprevent spoofing of smart contracts. By defining FBAC polices thatdetermine permissible function chains, any other function chain can beinvalidated by applying an access control rule to terminate itsexecution. Spoofing of critical path functions or generic smartcontracts can be prevented at the system level in case they get forgedby defining access control rules that require certain internal functioncalls that are native to the underlying blockchain in such a way that itrenders the forged smart contract or critical path function incapable ofdoing something it should not be doing. When coupled with a root oftrust that can be obtained from access control rules defined on ablockchain, function invocation chains can be made more fool proof.

In general terms, the disclosed technology utilizes one or more sets ofaccess control rules or policies to control function calls at a systemlevel by utilizing function boundary detection instrumentation in akernel. The function boundary detection instrumentation can generate afunction call stack that represents a chain of function calls in thekernel. The access control rules can be applied to the function callstack to allow or prohibit specific function call chains. If thefunction call chain or parameters do not meet the requirements definedin the access control rules, then the function call can be blocked orterminated. The access control rules can be defined to producesophisticated access control policies based on complex function callchains and data parameters.

The following Detailed Description describes technologies for functionbased access control at a system level in a blockchain platformutilizing access control rules. The access control rules can bemaintained on a blockchain for security, accessibility and immutability.

Note that, in some scenarios, different entities can provide the accesscontrol rules. For example, a Certificate Authority or other trustedsource can be utilized to own and control the access control rules. Insome examples, modifications or additions to the access control rulescan be stored in additional access control rule blocks on a blockchainthat require a signature of the trusted entity.

The resulting access control rule blocks can provide a record of theaccess control rules or policy defined for a blockchain platform or VMand provide a traceable and auditable history of the access controlrules.

A technical advantage of the disclosed function based access controltechnology includes securely controlling access at a system level.Another technical advantage of the disclosed function based accesscontrol technology is its ability to control complex function callchains. Yet another technical advantage of the disclosed function basedaccess control is the distributed nature of the blockchain, whichprevents an unauthorized entity from modifying or corrupting the accesscontrol rules at any single point. Other technical effects other thanthose mentioned herein can also be realized from implementation of thetechnologies disclosed herein.

As will be described in more detail herein, it can be appreciated thatimplementations of the techniques and technologies described herein mayinclude the use of solid state circuits, digital logic circuits,computer components, and/or software executing on one or more inputdevices. Signals described herein may include analog and/or digitalsignals for communicating a changed state of the data file or otherinformation pertaining to the data file.

While the subject matter described herein is presented in the generalcontext of program modules that execute in conjunction with theexecution of an operating system and application programs on a computersystem, those skilled in the art will recognize that otherimplementations may be performed in combination with other types ofprogram modules. Generally, program modules include routines, programs,components, data structures, and other types of structures that performparticular tasks or implement particular abstract data types. Moreover,those skilled in the art will appreciate that the subject matterdescribed herein may be practiced with other computer systemconfigurations, including multiprocessor systems, mainframe computers,microprocessor-based or programmable consumer electronics,minicomputers, hand-held devices, and the like.

In the following detailed description, references are made to theaccompanying drawings that form a part hereof, and in which are shown byway of illustration specific configurations or examples. Referring nowto the drawings, in which like numerals represent like elementsthroughout the several figures, aspects of a computing system,computer-readable storage medium, and computer-implemented methodologiesfor function based access control at a system level will be described.As will be described in more detail below with respect to the figures,there are a number of applications and services that may embody thefunctionality and techniques described herein.

FIG. 1 is an architectural diagram showing an illustrative example of asystem architecture 100 wherein a blockchain platform 130 maintains atransaction data blockchain 140 that can be accessed via a wide areanetwork 102. In this example, the blockchain platform 130 also maintainsan access control policy blockchain 150 that stores access control rulesthat can be utilized in the disclosed function based access controltechnology. Access control rules are applied at a system level duringexecution of functions in the transaction data blocks 142 of transactiondata blockchain 140 to perform function based access control.

In the embodiment of FIG. 1, blockchains 140 and 150 can each be apublicly available blockchain that supports scripting, such as theETHEREUM blockchain, which supports a SOLIDITY scripting language, orBITCOIN, which supports a scripting language called SCRIPT. Blockchains140 and 150 can also each be a private blockchain, or a combination ofpublic and private blockchains can be utilized. Transaction data blocks142 and access control rule blocks 152 can also reside on the sameblockchain.

In this example, a Certificate Authority is a trust entity that controlsthe access control policy blockchain 150. The Certificate Authority canadd or modify the access control policy by adding access control ruleblocks 152 to blockchain 150 that add, delete or modify access controlrules. The access control rule blocks 152 require the cryptographicsignature of the Certificate Authority to be valid.

A Certificate Authority 110, such as a client device, one or moreservers, or remote computing resources, is controlled by a trustedentity that creates the access control rules. In one example,Certificate Authority 110 initiates an access control policy blockchain150 by creating genesis block 152A. In other examples, the transactiondata blocks 142 and access control rule blocks 152 can be added to anexisting blockchain.

The transaction data blockchain can be utilized to securely storedifferent types of data in transaction data blocks 142, such as datapertaining to transactions or other data suitable for storage on ablockchain ledger. A transaction data block 142 can include methods orfunction calls that are executed by blockchain platform 130.

For access control policy blockchain 150, access control rule blocks 152can include access control rules for a domain, blockchain platformservice, enterprise or other entity that wishes to apply the disclosedfunction based access control to the execution of methods in smartcontracts.

In some embodiments, the Certificate Authority 110 can be replaced byanother computing node, such as a computer on a peer-to-peer network, orother computing device.

In the example of FIG. 1, the transaction data block is generated by anentity that owns a transaction and the block is secured on transactiondata blockchain 140. The transaction data stored in transaction datablocks 142 can relate to transactions performed by entities, such asclient/servers 120A, 120B or 120C. In this example, the client/servers120 can communicate with Certificate Authority 110 as well as a networkof servers for blockchain platform 130 that supports and maintainsblockchains 140 and 150. For example, the ETHEREUM blockchain platformfrom the ETHEREUM FOUNDATION of Switzerland provides a decentralized,distributed computing platform and operating system that providesscripting functionality.

In one example, Certificate Authority 110 owns and controls the accesscontrol rule blocks 152 in access control policy blockchain 150. Eachaccess control rule block 152 includes one or more access control rulesrelating to function calls that are allowed or prohibited in blockchainplatform 130. When access control rules are defined, the CertificateAuthority 110 creates an access control rule block 152 containing theaccess control rules and links it to access control policy blockchain150. When access control rules are added, modified or deleted, a newaccess control rule block 152 is created that incorporates the changesand the new block 152 is signed by Certificate Authority 110 and linkedto the previous access control rule block in the access control policyblockchain 150.

Although Certificate Authority 110 maintains control over the accesscontrol rules, the access control policy blockchain 150 can be madeaccessible to other entities, such as client/servers 120, so that theseentities can identify, trace or audit the relevant access control rulesstored in the blocks in the blockchain 150. Also, the access controlrules in blockchain 150 can be accessed by blockchain platform 130 toorder to apply the access control rules to perform the disclosedfunction based access control.

In some examples, the access control policy blockchain 150 may beviewable to other entities through the use of applications that canaccess blockchain information. By providing access to the access controlpolicy blockchain 150, this approach allows users to readily accesscontrol rules maintained on the access control policy blockchain 150under the control of the trusted entity, e.g. the user of CertificateAuthority 110.

In another example, aspects of the access control policy blockchain 150may be restricted to being viewable only to entities that are authorizedto access the blockchain 150, such as Certificate Authority 110 andblockchain platform 130.

FIG. 2A is a data architecture diagram illustrating a simplified exampleof a transaction data blockchain ledger 200 based on the blocks 142A-Eof the transaction data blockchain ledger 140 of FIG. 1. The transactiondata blockchain ledger 200 example of FIG. 2A is simplified to showblock headers, metadata and signatures of blocks 210A-E in order todemonstrate storage of transaction data using a blockchain. In outline,a blockchain ledger may be a globally shared transactional database.Signatures can, in some examples, involve all or part of the data storedin the data the blocks 142A-E and can also involve public key addressescorresponding to resource origination entities involved in the creationof resources.

The blockchain ledger 200 may be arranged as a Merkle tree datastructure, as a linked list, or as any similar data structure thatallows for cryptographic integrity. The blockchain ledger 200 allows forverification that the transaction data, and similarly access controlrule on access control policy blockchain 150, has not been corrupted ortampered with because any attempt to tamper will change a MessageAuthentication Code (or has) of a block, and other blocks pointing tothat block will be out of correspondence. In one embodiment of FIG. 2A,each block may point to another block. Each block may include a pointerto the other block, and a hash (or Message Authentication Code function)of the other block.

Each block in the blockchain ledger may optionally contain a proof datafield. The proof data field may indicate a reward that is due. The proofmay be a proof of work, a proof of stake, a proof of research, or anyother data field indicating a reward is due. For example, a proof ofwork may indicate that computational work was performed. As anotherexample, a proof of stake may indicate that an amount of cryptocurrencyhas been held for a certain amount of time. For example, if 10 units ofcryptocurrency have been held for 10 days, a proof of stake may indicate10*10=100 time units have accrued. A proof of research may indicate thatresearch has been performed. In one example, a proof of research mayindicate that a certain amount of computational work has beenperformed—such as exploring whether molecules interact a certain wayduring a computational search for an efficacious drug compound.

The blocks 210 of transaction data blockchain 200 in the example of FIG.2A shows securing transaction data with a new transaction data block onthe blockchain. In one example, a transaction entity, such as a user ofclient/servers 120 of FIG. 1, provides a transaction identifier andtransaction data for the transaction when it creates transaction datablock 210A. The transaction entity signs the transaction data block 210Aand the blockchain system within which blockchain 200 is createdverifies the transaction data block based on a proof function.

Note that the access control policy blockchain 150 illustrated in FIG. 1can take a similar form with access control rule blocks 152 thatincludes access control rules. Access control rule blocks 152 forsuccessive additions, modifications or deletions can be linked togetheron the same or a different blockchain such that a history of the accesscontrol rules is immutably and traceably stored using a blockchain.

Note that a variety of approaches may be utilized that remain consistentwith the disclosed technology. In some examples relating to accesscontrol rules, the user of Certificate Authority 110 is a requiredentity or the only entity permitted to verify or validate access controlrule blocks 152. In other examples, other entities, such as systemadministrators who define access control rules, is a required entity toverify or validate access control rule blocks 152.

In the example of FIG. 2A, transaction data blocks 210 of transactiondata blockchain 200 include transaction identifiers and transaction dataalong with a signature of an entity that owns the transaction. To addanother transaction data block for another transaction, a transactionentity creates transaction data block 210B, which identifies thetransaction and includes the transaction data. The transaction entitysigns transaction data block 210B and commits block 210B to blockchain200 for verification by the blockchain platform.

To add more transaction data blocks for an additional transactions, thesame or another transaction entity creates transaction data block 210Cto secure transaction data for transaction TRANS_ID_3 along with datafor the transaction. Similarly, transaction data block 242D is createdby another transaction entity to store the transaction data fortransaction TRANS_ID_4 and transaction data block 242E is created tostore the transaction data for TRANS_ID_5.

The transaction data blocks 142 can be smart contracts that includemethods or functions that are executed by the blockchain platform 130.FIG. 2B is a data architecture diagram showing an illustrative exampleof a transaction data block 142 with functions that are executed by ablockchain platform or framework. For example, the functions Function_1,Function_2, Function_3, and Function_4 can be executed by a VM operatingin blockchain platform 130. Access control policy blockchain, such asblockchain 150 in FIG. 1 enables access control rules to be securelystored to maintain access control policy that can be utilized for thefunction based access control of the disclosed technology. The accesscontrol rules are obtained from the blockchain 150 and applied tofunction calls in the VM at a system level.

FIG. 3A is a functional block diagram illustrating an example of thefunction based access control of the disclosed technology being appliedto the function calls in transaction data block 242 being executed inblockchain platform 330. In this example, blockchain platform 330includes VMs 332A and 332B that are executing in kernel 340 andexecuting the function calls from transaction data block 242.

Kernel 340 includes function boundary detection instrumentation 342,such as eBPF, that detects when a function is entered or exits andcreates call stack 344 to represent a chain of function calls 346. Inthis example, call stack 344 includes a call stack for the functionscalls in the execution of transaction data block 242 from Function_1 toFunction_2, Function_2 to Function_3, and Function_3 to Function_4.

Blockchain platform 330 includes function boundary access control module348, which, in this example, obtains access control rules fromblockchain 350 and applies the rules to the function call chain in callstack 344. When a function boundary is detected by function boundarydetection instrumentation 342, FBAC 348 applies the access control rulesto the call stack 344 to determine whether the function should beblocked and sends a signal to, in this example, VM 332B to allow or denyexecution or completion of the function.

Note that FBAC module 346 utilizes system level support to run. In someexamples, it can be its own privileged VM that runs the FBACfunctionality and can exercise control over the other VMs, e.g. VMs 332Aand 332B, that run the smart contracts, e.g. transaction data block 242.In other examples, however, the same VM can run both the smart contractsand the FBAC functionality. In either example, the VM will use thefunction boundary detection instrumentation 342 in the kernel of theunderlying operating system.

As noted above, the access control rules of the FBAC policies can bestored in a blockchain much like a smart contract and backed by the samemultisignature cryptographic signature methods currently used byblockchain frameworks to ensure that deployed access control rules aretrackable to their origins. Updates of policies can also be coded intothe blockchain so that only the latest policies are applied dynamicallyby the FBAC module 348. By maintaining the FBAC policies on theblockchain itself, they are automatically immutably secured. Since thesepolicies are static and not code that gets executed, they themselvescannot be hacked or exploited, unlike smart contracts, which are asvulnerable as the VM executing the smart contract.

In differing implementations, the FBAC policies can be realized by anaddendum to the VM that executes the smart contracts, or as a standaloneprivileged system level module that can only be programmed by FBACrules/policies that are read in from the blockchain. In eitherimplementation, no back door is available in the FBAC module forexploitation by malicious actors.

FIG. 3B is a data architecture diagram showing illustrative examples ofaccess control rule blocks 352 in access control policy blockchain 350of FIG. 3A. Access control rules can take many forms in the disclosedtechnology.

For example, access control rule block 352A contains a white list offunction based rules defining functions and function call chains thatare permitted with respect to the function calls from transaction datablock 242 of FIG. 3A. Function calls or function call chains in callstack 344 that do not conform to the white list function rules of ruleblock 352A will result in FBAC module 348 denying execution orcompletion of a function call.

For example, a call from Function_2 to Function_4 in call stack 344 doesnot match any of the white list rules and will result in FBAC module 348generating a DENY signal to VM 342B, where the function call chain isexecuting. However, a call stack of Function_1 to Function_2 toFunction_3 does match one of the white list rules and will result inFBAC module 348 generating an ALLOW signal to VM 342B. Note that therules in block 352A are structured to permit each interim function callto occur for a permitted function call chain of Function_1 to Function_2to Function_3 to Function_4.

Another form for the access control rules is illustrated in a black listof function based rules defining functions and function call chains thatare prohibited with respect to the function calls from transaction datablock 242 of FIG. 3A. Function calls or function call chains in callstack 344 that match one of the black list function rules of rule block352A will result in FBAC module 348 denying execution or completion of afunction call.

For example, a call to Function_5, e.g. a call to Deposit( ), isprohibited and will result in FBAC module 348 generating a DENY signalto VM 342B. Similarly, an out of permitted sequence call from Function_2to Function_4 in call stack 344 matches one of the black list rules andwill result in FBAC module 348 generating a DENY signal to VM 342B,where the function call chain is executing. However, a call fromFunction_1 to Function_2 does not match any of the black list rules andwill result in FBAC module 348 generating an ALLOW signal to VM 342B.

Yet another form for the access control rules is illustrated in a whitelist of rules that are function and data based that define functioncalls and parameters that are permitted with respect to the functioncalls from transaction data block 242 of FIG. 3A. Function calls orfunction call chains and parameters in call stack 344 that do notconform to the white list function rules of rule block 352C will resultin FBAC module 348 denying execution or completion of a function call.

For example, a call from Function_1 must have parameter a=X. A functioncall chain from Function_1 with parameter a=X to Function_2 withparameter g=a to Function_3 with parameter n=g in call stack 344 matchesthe (Function_1[a=X], Function_2[g=a], Function_3[n=g]) white list ruleand will result in FBAC module 348 generating an ALLOW signal to VM342B, where the function call chain is executing. However, a call stackof Function_1 to Function_2 to Function_3 with parameters that do notmatch the functions and parameters in any of the white list rules andwill result in FBAC module 348 generating a DENY signal to VM 342B. Notethat the rules in block 352A are structured to permit each interimfunction call to occur for a permitted function call chain of Function_1to Function_2 to Function_3 to Function_4.

Note that the example white list rules shown in access rule block 352Cenforce a function call parameter relationship where a call parameter ineach function call matches a parameter in a previous function call, e.g.(Function_1 [a=X], Function_2[g=a], Function_3[n=g], Function_4[x=n]).For example, such a rule can be used to enforce that a consistenttransaction identifier value be utilized throughout a function callchain, which may prevent a hack where a malicious actor attempts toredirect a transaction being executed in a smart contract.

Access rule block 352D illustrates an example of a black list of rulesthat are function and data based that define function calls andparameters that are prohibited with respect to the function calls fromtransaction data block 242 of FIG. 3A. Function calls or function callchains and parameters in call stack 344 that match one of the black listfunction and data based rules of rule block 352D will result in FBACmodule 348 denying execution or completion of a function call.

For example, a call from Function_1 must not have a value for parametera that is greater than 60. A function call from Function_2 must not havea parameter value g that equals 0. A function call from Function_3 mustnot have a value of parameter n that is greater than 40. A function callfrom Function_4 must not have a value of parameter x equal to 25. Therules in the example of rule block 352D illustrate access control policythat enforces limits on input parameters to functions in a smartcontract.

Generally speaking, if the black lists and white lists are empty, thenall function calls are allowed. If the black lists are empty and thewhite lists contain access control rules, then only the functions orfunction chains defined in the white list rules are permitted. If theblack lists contain access control rules, but the white lists are empty,then all functions are prohibited. If both the black list and the whitelist contain access control rules, then the functions and functionchains defined in the black list are prohibited, the functions andfunction chains defined in the white list are allowed. If access controlrules in the black list and the white list are in conflict, then theblack list rule generally takes precedence.

Note that the function or data based access rules can be stored in aside chain of a blockchain. Also note that the example access controlrules illustrated in FIG. 3B are relatively simple and it will bereadily appreciated that the disclosed technology enables highly complexand varied access control policy to be implemented at a system level.For example, multiple different function call chains or multiple callparameter values can be permitted or prohibited.

Also, the ACCESS or DENY signal generated by FBAC module 348 can beconfigured to be more complex or more complex access control policiesdefined. For example, instead of a simple DENY signal, FBAC module 348can be configured to delay generation of an ALLOW signal for purposes ofrate limitation. Similarly, instead of a simple ALLOW signal, FBACmodule 348 can be configured to vary a time for generation of an ALLOWsignal for purposes of differentiated QoS or resource allocation.

Likewise, in some implementations, state data can be maintained by FBACmodule 348 and access control policies defined using state data. Forexample, state data regarding the number of times a function has beencalled within a time interval to generate a DENY signal for purposes ofa circuit breaker function or to delay generation of an ALLOW signal forpurposes of a rate limitation function.

Further, some access control policy can be defined to enforcepermissions. For example, certain users or entities can be permittedaccess to particular data in a transaction data block using a white listrule or prohibited from accessing the data by a black list rule.

It will be readily appreciated that the disclosed technology enablescomplex and sophisticated access control policy to be defined andenforced at a system level. Many variations can be implemented thatdiffer from the examples illustrated or go beyond the examplesillustrated.

The access control policies illustrated in FIG. 3B can be defined anddetermine in a variety of ways. For example, a user with administrativepermissions can define the access control rules and save them in theFBAC module 348 or as an addendum to a VM in kernel 340. In anotherexample, a trusted entity, such as a Certificate Authority, receives theaccess control rules and manages distribution of the rules to the FBACmodule 348 or VMs in an execution platform for smart contracts, such asblockchain platform 330.

In still another example, the user with administrative permissions canstore the access control rules in rule blocks owned by the user onaccess control policy blockchain 350. Or, in a different example, theadministrative user provides the access control rules to a trustedentity, such as a Certificate Authority, which stores the access controlrules in rule blocks on access control policy blockchain 350 that areowned by the trusted entity.

FIG. 4A is a control flow diagram showing an illustrative example of aprocess 400 whereby access control policy is defined and distributed foruse in function based access control in accordance with aspects of thedisclosed technology. At 402, access control rules for an access controlpolicy are defined as described above or in other ways as are suitablefor a particular implementation. At 404, the access control rules aredistributed as described above such that the access control rules aresecure and accessible to FBAC module 348 or another module that performsthe system level function based access control according to thedisclosed technology.

FIG. 4B is a control flow diagram showing an illustrative example of aprocess 410 for system level function based access control in accordancewith aspects of the disclosed technology. At 412, a smart contract isexecuted in a kernel execution framework, such as a kernel framework forsmart contract execution provided by a blockchain platform, that isconfigured with function boundary detection instrumentation, e.g. eBPF.At 414, the function boundary detection instrumentation detects atfunction call at a system level, e.g. at the entrance or exit of afunction call made when methods in the smart contract are executed.

At 416, a function call stack is created for the detected functioncalls. The function call stack can include chain of function calls thathave been called in the sequence that they are called and can alsoinclude parameters passed in the function calls. In someimplementations, other data, such as state data regarding the functionsand resources, can also be maintained.

At 418, the function call stack is checked against the function or databased access control rules that have been defined. As described above,the access control rules can include white lists or black lists forfunction calls or data indicated in the function call stack. Inaddition, in some implementations, access control rules can be definedthat utilize state data for certain purposes, such as a rate limitationor circuit breaker functionality.

At 420, if the access control rules indicate that the function call isallowed, then control branches to 422 to allow execution of thefunction. If the access control rules indicate that the function call isnot allowed, then control branches to 424 to deny or block execution orcompletion of the function call.

Process 410 is a simplified process for function based access control.As discussed above, the access control rules and function based accesscontrol process can be configured to control function calls on a moresophisticated level, such as delaying or accelerating execution of afunction call for QoS, dynamic resource allocation or rate limitationpurposes.

FIG. 4C is a control flow diagram illustrating an example of avalidation process 480 for blocks added to the transaction datablockchain ledger or access control policy blockchain ledger implementedusing untrusted blockchain nodes. In process 480, when a transactiondata block 142 is created for transaction data blockchain 140 or anaccess control rule block 152 is created for access control policyblockchain 150 in FIG. 1, the transaction is broadcast, at 482, to thecluster of untrusted nodes. At 484, nodes compete to compute avalidation solution for the transaction. At 486, a winning nodebroadcasts the validation solution for the transaction data block oraccess control rule block and adds the data block to its copy of thecorresponding data blockchain ledger, e.g. transaction data blockchain140 or access control policy blockchain 150 in FIG. 1.

At 488, in response to the winning node's broadcast, the other nodes addthe transaction data block or access control rule block to their copiesof the transaction data blockchain ledger or access control policyblockchain ledger in the transaction order established by the winningnode. The decentralized validation protocol can maintain the integrity,immutability and security of the transaction data blockchain ledger oraccess control policy blockchain ledger.

It should be appreciated that the processes shown for examples and avariety of other approaches may be utilized without departing from thedisclosed technology.

Depending upon the scripting capabilities of the blockchain platform,the methods or function in the data blocks of the transaction datablockchain may include more extensive code execution. For example, atransaction data system that provides for shared access to thetransaction by multiple users may involve more extensive code executioncapability in the blockchain than a transaction data system that limitsaccess to a single user. Such a transaction data system may involveaccess control policy utilizing system level function and data basedaccess control to implement a system of permissions for controllingaccess to different parts of the transaction data.

It should be appreciated that the utilization of system level functionbased access control with access control rules based on functions ordata can provide a high degree of flexibility, complexity and variationin the configuration of implementations without departing from theteaching of the disclosed technology.

Note that the disclosed technology is not limited to the transactiondata example described above, but may be applied to a variety of smartcontracts executing on blockchain platforms. The technology may beapplied to provide secure system level access control in a wide varietyof use contexts.

FIG. 5 is a data architecture diagram showing an illustrative example ofan interface for initiating execution of smart contract scripts on ablockchain platform, such as the transaction data blocks in FIGS. 1, 2A,2B and 3A. In this example, an Application Program Interface (API) 510provides an interface to the blockchain platform 520 that supports thetransaction data blockchain. The blockchain platform 520 supports asmart contract 522, such as transaction data block 242 in FIG. 2B, whichincludes scripts 524 with code that, when executed by the blockchainplatform 520, performs operations with respect to the transaction datablockchain.

In the example of FIG. 5, four scripts are shown in smart contract 522.A client/server 502 initiates a transaction on the transaction datablockchain that causes Function_1 to execute and call Function_2.Function_2 calls Function_3, Function_3 calls Function_4, which, in thisexample, returns a message 506 to client/server 502. The functions areexecuted in an execution framework on blockchain platform 520, such asthe framework shown in FIG. 3A, which uses access control rules toperform system level function based access control on the functioncalls.

Blockchain Ledger Data Structure

FIG. 6A is a data architecture diagram illustrating a simplified exampleof a blockchain ledger 600 based on the blocks 142A-E of the transactiondata blockchain 140 or blocks 152A-E of the access control policyblockchain 150 of FIG. 1. The blockchain ledger 600 example of FIG. 6Ais simplified to show block headers, metadata and signatures of blocks142A-E or blocks 152A-E in order to demonstrate a secure transactiondata or access rule ledger using a blockchain. In outline, a blockchainledger may be a globally shared transactional database.

FIG. 6A is an illustrative example of a blockchain ledger 600 with adata tree holding transaction data that is verified using cryptographictechniques. In FIG. 6A, each block 610 includes a block header 612 withinformation regarding previous and subsequent blocks and stores atransaction root node 614 to a data tree 620 holding transactional data.Transaction data may store smart contracts, data related totransactions, or any other data. The elements of smart contracts mayalso be stored within transaction nodes of the blocks.

In the example of FIG. 6A, a Merkle tree 620 is used tocryptographically secure the transaction data. For example, TransactionTx1 node 634A of data tree 620A of block 610A can be hashed to Hash1node 632A, Transaction Tx2 node 638A may be hashed to Hash2 node 636A.Hash1 node 632A and Hash2 node 636A may be hashed to Hash12 node 630A. Asimilar subtree may be formed to generate Hash34 node 640A. Hash12 node630A and Hash34 node 640A may be hashed to Transaction Root 614A hashsorted in the data block 610A. By using a Merkle tree, or any similardata structure, the integrity of the transactions may be checked byverifying the hash is correct.

FIG. 6B is a data architecture diagram showing an illustrative exampleof smart contract code, transactions and messages that are bundled intoa block so that their integrity is cryptographically secure and so thatthey may be appended to a blockchain ledger. In FIG. 6B, smart contracts642 are code that executes on a computer. More specifically, the code ofa smart contract may be stored in a blockchain ledger and executed bynodes of a distributed blockchain platform at a given time. The resultof the smart code execution may be stored in a blockchain ledger.Optionally, a currency may be expended as smart contract code isexecuted. In the example of FIG. 6B, smart contracts 642 are executed ina virtual machine environment, although this is optional.

In FIG. 6B, the aspects of smart contracts 642 are stored in transactiondata nodes in data tree 620 in the blocks 610 of the blockchain ledgerof FIG. 6A. In the example of FIG. 6B, Smart Contract 642A is stored indata block Tx1 node 634A of data tree 620A in block 610A, Smart Contract642B is stored in Tx2 node 638A, Contract Account 654 associated withSmart Contract 642B is stored in Tx3 node 644A, and External Account isstored in Tx4 node 648A.

Storage of Smart Contracts and Transaction Data in the Blockchain Ledger

To ensure the smart contracts are secure and generate secure data, theblockchain ledger must be kept up to date. For example, if a smartcontract is created, the code associated with a smart contract must bestored in a secure way. Similarly, when smart contract code executes andgenerates transaction data, the transaction data must be stored in asecure way.

In the example of FIG. 6B, two possible embodiments for maintenance ofthe blockchain ledger are shown. In one embodiment, untrusted minernodes (“miners”) 680 may be rewarded for solving a cryptographic puzzleand thereby be allowed to append a block to the blockchain.Alternatively, a set of trusted nodes 690 may be used to append the nextblock to the blockchain ledger. Nodes may execute smart contract code,and then one winning node may append the next block to a blockchainledger.

Though aspects of the technology disclosed herein resemble a smartcontract, in the present techniques, the policy of the contract maydetermine the way that the blockchain ledger is maintained. For example,the policy may require that the validation or authorization process forblocks on the ledger is determined by a centralized control of a clusterof trusted nodes. In this case, the centralized control may be a trustednode, such as Certificate Authority 110, authorized to attest and signthe transaction blocks to validate them and validation by miners may notbe needed.

Alternatively, the policy may provide for validation process decided bya decentralized cluster of untrusted nodes. In the situation where theblockchain ledger is distributed to a cluster of untrusted nodes, miningof blocks in the chain may be employed to validate the blockchainledger.

Blockchains may use various time-stamping schemes, such asproof-of-work, to serialize changes. Alternate consensus methods includeproof-of-stake, proof-of-burn, proof-of-research may also be utilized toserialize changes.

As noted above, in some examples, a blockchain ledger may be validatedby miners to secure the blockchain. In this case, miners maycollectively agree on a validation solution to be utilized. However, ifa small network is utilized, e.g. private network, then the solution maybe a Merkle tree and mining for the validation solution may not berequired. When a transaction block is created, e.g. a transaction datablock 142 for transaction data blockchain 140 or an access control ruleblock 152 for access control policy blockchain 150, the block is anunconfirmed and unidentified entity. To be part of the acknowledged“currency”, it may be added to the blockchain, and therefore relates tothe concept of a trusted cluster.

In a trusted cluster, when a data block 142 or 152 is added, every nodecompetes to acknowledge the next “transaction” (e.g. a new transactiondata or access control rule block). In one example, the nodes compete tomine and get the lowest hash value: min {previous_hash, contents_hash,random_nonce_to_be_guessed}→result. Transaction order is protected bythe computational race (faith that no one entity can beat the collectiveresources of the blockchain network). Mutual authentication parametersare broadcast and acknowledged to prevent double entries in theblockchain.

Alternatively, by broadcasting the meta-data for authenticating a secureledger across a restricted network, e.g. only the signed hash isbroadcast, the blockchain may reduce the risks that come with data beingheld centrally. Decentralized consensus makes blockchains suitable forthe recording of secure transactions or events. The meta-data, which maycontain information related to the data file, may also be ciphered forrestricted access so that the meta-data does not disclose informationpertaining to the data file.

The mining process, such as may be used in concert with the validationprocess 480 of FIG. 4C, may be utilized to deter double accounting,overriding or replaying attacks, with the community arrangement on theagreement based on the “good faith” that no single node can control theentire cluster. A working assumption for mining is the existence ofequivalent power distribution of honest parties with supremacy overdishonest or compromised ones. Every node or miner in a decentralizedsystem has a copy of the blockchain. No centralized “official” copyexists and no user is “trusted” more than any other. Transactions arebroadcast, at 482, to the network using software. Mining nodes compete,at 484, to compute a validation solution to validate transactions, andthen broadcast, at 486, the completed block validation to other nodes.Each node adds the block, at 488, to its copy of the blockchain withtransaction order established by the winning node.

Note that in a restricted network, stake-holders who are authorized tocheck or mine for the data file may or may not access the transactionblocks themselves, but would need to have keys to the meta-data (sincethey are members of the restricted network, and are trusted) to get thedetails. As keys are applied on data with different dataclassifications, the stake-holders can be segmented.

A decentralized blockchain may also use ad-hoc secure message passingand distributed networking. In this example, the access control policyblockchain ledger may be different from a conventional blockchain inthat there is a centralized clearing house, e.g. authorized centralcontrol for validation. Without the mining process, the trusted clustercan be contained in a centralized blockchain instead of a public ordemocratic blockchain. One way to view this is that a decentralizedportion is as “democratic N honest parties” (multiparty honest party isa cryptography concept), and a centralized portion as a “trustedmonarchy for blockchain information correction”. For example, there maybe advantages to maintaining the data file as centrally authorized andkept offline.

In some examples, access to a resource and access control rule on ablockchain can be restricted by cryptographic means to be only open toauthorized servers. Since the transaction data or access control policyblockchain ledgers are distributed, the authorized servers can validateit. A public key may be used as an address on a public blockchainledger.

Note that growth of a decentralized blockchain may be accompanied by therisk of node centralization because the computer resources required tooperate on bigger data become increasingly expensive.

The present techniques may involve operations occurring in one or moremachines. As used herein, “machine” means physical data-storage andprocessing hardware programmed with instructions to perform specializedcomputing operations. It is to be understood that two or more differentmachines may share hardware components. For example, the same integratedcircuit may be part of two or more different machines.

One of ordinary skill in the art will recognize that a wide variety ofapproaches may be utilized and combined with the present approachinvolving a access control policy blockchain ledger. The specificexamples of different aspects of a access control policy blockchainledger described herein are illustrative and are not intended to limitthe scope of the techniques shown.

Smart Contracts

Smart contracts are defined by code. As described previously, the termsand conditions of the smart contract may be encoded (e.g., by hash) intoa blockchain ledger. Specifically, smart contracts may be compiled intoa bytecode (if executed in a virtual machine), and then the bytecode maybe stored in a blockchain ledger as described previously. Similarly,transaction data executed and generated by smart contracts may be storedin the blockchain ledger in the ways previously described.

Computer Architectures for Use of Smart Contracts and Blockchain Ledgers

Note that at least parts of processes 400, 410, and 480 of FIGS. 4A-C,the scripts of transaction data block 242 of FIG. 2B, smart contract 522of FIG. 5, smart contracts 642 of FIG. 6B, and other processes andoperations pertaining to transaction data and access control policyblockchain ledgers described herein may be implemented in one or moreservers, such as computer environment 800 in FIG. 8, or the cloud, anddata defining the results of user control input signals translated orinterpreted as discussed herein may be communicated to a user device fordisplay. Alternatively, the access control policy blockchain ledgerprocesses may be implemented in a client device. In still otherexamples, some operations may be implemented in one set of computingresources, such as servers, and other steps may be implemented in othercomputing resources, such as a client device.

It should be understood that the methods described herein can be endedat any time and need not be performed in their entireties. Some or alloperations of the methods described herein, and/or substantiallyequivalent operations, can be performed by execution ofcomputer-readable instructions included on a computer-storage media, asdefined below. The term “computer-readable instructions,” and variantsthereof, as used in the description and claims, is used expansivelyherein to include routines, applications, application modules, programmodules, programs, components, data structures, algorithms, and thelike. Computer-readable instructions can be implemented on varioussystem configurations, including single-processor or multiprocessorsystems, minicomputers, mainframe computers, personal computers,hand-held computing devices, microprocessor-based, programmable consumerelectronics, combinations thereof, and the like.

Thus, it should be appreciated that the logical operations describedherein are implemented (1) as a sequence of computer implemented acts orprogram modules running on a computing system and/or (2) asinterconnected machine logic circuits or circuit modules within thecomputing system. The implementation is a matter of choice dependent onthe performance and other requirements of the computing system.Accordingly, the logical operations described herein are referred tovariously as states, operations, structural devices, acts, or modules.These operations, structural devices, acts, and modules may beimplemented in software, in firmware, in special purpose digital logic,and any combination thereof.

As described herein, in conjunction with the FIGURES described herein,the operations of the routines (e.g. processes 400, 410, and 480 ofFIGS. 4A-C, the scripts of transaction data block 242 of FIG. 2B, smartcontract 522 of FIG. 5, smart contracts 642 of FIG. 6B) are describedherein as being implemented, at least in part, by an application,component, and/or circuit. Although the following illustration refers tothe components of FIGS. 1, 2B, 4A-C, 5 and 6B, it can be appreciatedthat the operations of the routines may be also implemented in manyother ways. For example, the routines may be implemented, at least inpart, by a computer processor or a processor or processors of anothercomputer. In addition, one or more of the operations of the routines mayalternatively or additionally be implemented, at least in part, by acomputer working alone or in conjunction with other software modules.

For example, the operations of routines are described herein as beingimplemented, at least in part, by an application, component and/orcircuit, which are generically referred to herein as modules. In someconfigurations, the modules can be a dynamically linked library (DLL), astatically linked library, functionality produced by an applicationprogramming interface (API), a compiled program, an interpreted program,a script or any other executable set of instructions. Data and/ormodules, such as the data and modules disclosed herein, can be stored ina data structure in one or more memory components. Data can be retrievedfrom the data structure by addressing links or references to the datastructure.

Although the following illustration refers to the components of theFIGURES discussed above, it can be appreciated that the operations ofthe routines (e.g. processes 400, 410, and 480 of FIGS. 4A-C, thescripts of transaction data block 242 of FIG. 2B, smart contract 522 ofFIG. 5, smart contracts 642 of FIG. 6B) may be also implemented in manyother ways. For example, the routines may be implemented, at least inpart, by a processor of another remote computer or a local computer orcircuit. In addition, one or more of the operations of the routines mayalternatively or additionally be implemented, at least in part, by achipset working alone or in conjunction with other software modules. Anyservice, circuit or application suitable for providing the techniquesdisclosed herein can be used in operations described herein.

FIG. 7 shows additional details of an example computer architecture 700for a computer, such as the devices 110 and 120A-C (FIG. 1), capable ofexecuting the program components described herein. Thus, the computerarchitecture 700 illustrated in FIG. 7 illustrates an architecture for aserver computer, mobile phone, a PDA, a smart phone, a desktop computer,a netbook computer, a tablet computer, an on-board computer, a gameconsole, and/or a laptop computer. The computer architecture 700 may beutilized to execute any aspects of the software components presentedherein.

The computer architecture 700 illustrated in FIG. 7 includes a centralprocessing unit 702 (“CPU”), a system memory 704, including a randomaccess memory 706 (“RAM”) and a read-only memory (“ROM”) 708, and asystem bus 710 that couples the memory 704 to the CPU 702. A basicinput/output system containing the basic routines that help to transferinformation between sub-elements within the computer architecture 700,such as during startup, is stored in the ROM 708. The computerarchitecture 700 further includes a mass storage device 712 for storingan operating system 707, data (such as a copy of transaction datablockchain data 720 or access control policy blockchain data 722), andone or more application programs.

The mass storage device 712 is connected to the CPU 702 through a massstorage controller (not shown) connected to the bus 710. The massstorage device 712 and its associated computer-readable media providenon-volatile storage for the computer architecture 700. Although thedescription of computer-readable media contained herein refers to a massstorage device, such as a solid-state drive, a hard disk or CD-ROMdrive, it should be appreciated by those skilled in the art thatcomputer-readable media can be any available computer storage media orcommunication media that can be accessed by the computer architecture700.

Communication media includes computer readable instructions, datastructures, program modules, or other data in a modulated data signalsuch as a carrier wave or other transport mechanism and includes anydelivery media. The term “modulated data signal” means a signal that hasone or more of its characteristics changed or set in a manner so as toencode information in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared and other wireless media. Combinations of any of the aboveshould also be included within the scope of computer-readable media.

By way of example, and not limitation, computer storage media mayinclude volatile and non-volatile, removable and non-removable mediaimplemented in any method or technology for storage of information suchas computer-readable instructions, data structures, program modules orother data. For example, computer media includes, but is not limited to,RAM, ROM, EPROM, EEPROM, flash memory or other solid state memorytechnology, CD-ROM, digital versatile disks (“DVD”), HD-DVD, BLU-RAY, orother optical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to store the desired information and which can be accessed bythe computer architecture 700. For purposes the claims, the phrase“computer storage medium,” “computer-readable storage medium” andvariations thereof, does not include waves, signals, and/or othertransitory and/or intangible communication media, per se.

According to various configurations, the computer architecture 700 mayoperate in a networked environment using logical connections to remotecomputers through the network 756 and/or another network (not shown).The computer architecture 700 may connect to the network 756 through anetwork interface unit 714 connected to the bus 710. It should beappreciated that the network interface unit 714 also may be utilized toconnect to other types of networks and remote computer systems. Thecomputer architecture 700 also may include an input/output controller716 for receiving and processing input from a number of other devices,including a keyboard, mouse, game controller, television remote orelectronic stylus (not shown in FIG. 7). Similarly, the input/outputcontroller 716 may provide output to a display screen, a printer, orother type of output device (also not shown in FIG. 7).

It should be appreciated that the software components described hereinmay, when loaded into the CPU 702 and executed, transform the CPU 702and the overall computer architecture 700 from a general-purposecomputing system into a special-purpose computing system customized tofacilitate the functionality presented herein. The CPU 702 may beconstructed from any number of transistors or other discrete circuitelements, which may individually or collectively assume any number ofstates. More specifically, the CPU 702 may operate as a finite-statemachine, in response to executable instructions contained within thesoftware modules disclosed herein. These computer-executableinstructions may transform the CPU 702 by specifying how the CPU 702transitions between states, thereby transforming the transistors orother discrete hardware elements constituting the CPU 702.

Encoding the software modules presented herein also may transform thephysical structure of the computer-readable media presented herein. Thespecific transformation of physical structure may depend on variousfactors, in different implementations of this description. Examples ofsuch factors may include, but are not limited to, the technology used toimplement the computer-readable media, whether the computer-readablemedia is characterized as primary or secondary storage, and the like.For example, if the computer-readable media is implemented assemiconductor-based memory, the software disclosed herein may be encodedon the computer-readable media by transforming the physical state of thesemiconductor memory. For example, the software may transform the stateof transistors, capacitors, or other discrete circuit elementsconstituting the semiconductor memory. The software also may transformthe physical state of such components in order to store data thereupon.

As another example, the computer-readable media disclosed herein may beimplemented using magnetic or optical technology. In suchimplementations, the software presented herein may transform thephysical state of magnetic or optical media, when the software isencoded therein. These transformations may include altering the magneticcharacteristics of particular locations within given magnetic media.These transformations also may include altering the physical features orcharacteristics of particular locations within given optical media, tochange the optical characteristics of those locations. Othertransformations of physical media are possible without departing fromthe scope and spirit of the present description, with the foregoingexamples provided only to facilitate this discussion.

In light of the above, it should be appreciated that many types ofphysical transformations take place in the computer architecture 700 inorder to store and execute the software components presented herein. Italso should be appreciated that the computer architecture 700 mayinclude other types of computing devices, including hand-held computers,embedded computer systems, personal digital assistants, and other typesof computing devices known to those skilled in the art. It is alsocontemplated that the computer architecture 700 may not include all ofthe components shown in FIG. 7, may include other components that arenot explicitly shown in FIG. 7, or may utilize an architecturecompletely different than that shown in FIG. 7.

FIG. 8 depicts an illustrative distributed computing environment 800capable of executing the software components described herein for systemlevel function based access control for a blockchain ledger. Thus, thedistributed computing environment 800 illustrated in FIG. 8 can beutilized to execute many aspects of the software components presentedherein. For example, the distributed computing environment 800 can beutilized to execute one or more aspects of the software componentsdescribed herein. Also, the distributed computing environment 800 mayrepresent components of the distributed blockchain platform discussedabove.

According to various implementations, the distributed computingenvironment 800 includes a computing environment 802 operating on, incommunication with, or as part of the network 804. The network 804 maybe or may include the network 856, described above. The network 804 alsocan include various access networks. One or more client devices806A-806N (hereinafter referred to collectively and/or generically as“clients 806”) can communicate with the computing environment 802 viathe network 804 and/or other connections (not illustrated in FIG. 8). Inone illustrated configuration, the clients 806 include a computingdevice 806A, such as a laptop computer, a desktop computer, or othercomputing device; a slate or tablet computing device (“tablet computingdevice”) 806B; a mobile computing device 806C such as a mobiletelephone, a smart phone, an on-board computer, or other mobilecomputing device; a server computer 806D; and/or other devices 806N,which can include a hardware security module. It should be understoodthat any number of devices 806 can communicate with the computingenvironment 802. Two example computing architectures for the devices 806are illustrated and described herein with reference to FIGS. 7 and 8. Itshould be understood that the illustrated devices 806 and computingarchitectures illustrated and described herein are illustrative only andshould not be construed as being limited in any way.

In the illustrated configuration, the computing environment 802 includesapplication servers 808, data storage 810, and one or more networkinterfaces 812. According to various implementations, the functionalityof the application servers 808 can be provided by one or more servercomputers that are executing as part of, or in communication with, thenetwork 804. The application servers 808 can host various services,virtual machines, portals, and/or other resources. In the illustratedconfiguration, the application servers 808 host one or more virtualmachines 814 for hosting applications or other functionality. Accordingto various implementations, the virtual machines 814 host one or moreapplications and/or software modules for a data management blockchainledger. It should be understood that this configuration is illustrativeonly and should not be construed as being limiting in any way.

The application servers 808 can also host system level function basedaccess control functionality module 816, such as those described withrespect to blockchain platform 330 of FIG. 3A. FBAC module 816 can applyaccess control policy to smart contracts executing in virtual machines814.

According to various implementations, the application servers 808 alsoinclude one or more transaction data management services 820 and one ormore blockchain services 822. The transaction data management services820 can include services for managing transaction data on a transactiondata blockchain, such as transaction data blockchain 140 in FIG. 1. Theaccess control policy management services 823 can include services formanaging access control rules on an access control policy blockchain,such as access control policy blockchain 150 in FIG. 1 or otherwisemaintain access control policy that is applied by FBAC module 816. Theblockchain services 822 can include services for participating inmanagement of one or more blockchains, such as by creating genesisblocks, transaction data or access control rule blocks, and performingvalidation.

As shown in FIG. 8, the application servers 808 also can host otherservices, applications, portals, and/or other resources (“otherresources”) 824. The other resources 824 can include, but are notlimited to, data encryption, data sharing, or any other functionality.

As mentioned above, the computing environment 802 can include datastorage 810. According to various implementations, the functionality ofthe data storage 810 is provided by one or more databases or data storesoperating on, or in communication with, the network 804. Thefunctionality of the data storage 810 also can be provided by one ormore server computers configured to host data for the computingenvironment 802. The data storage 810 can include, host, or provide oneor more real or virtual data stores 826A-826N (hereinafter referred tocollectively and/or generically as “datastores 826”). The datastores 826are configured to host data used or created by the application servers808 and/or other data. Aspects of the datastores 826 may be associatedwith services for a access control policy blockchain. Although notillustrated in FIG. 8, the datastores 826 also can host or store webpage documents, word documents, presentation documents, data structures,algorithms for execution by a recommendation engine, and/or other datautilized by any application program or another module.

The computing environment 802 can communicate with, or be accessed by,the network interfaces 812. The network interfaces 812 can includevarious types of network hardware and software for supportingcommunications between two or more computing devices including, but notlimited to, the clients 806 and the application servers 808. It shouldbe appreciated that the network interfaces 812 also may be utilized toconnect to other types of networks and/or computer systems.

It should be understood that the distributed computing environment 800described herein can provide any aspects of the software elementsdescribed herein with any number of virtual computing resources and/orother distributed computing functionality that can be configured toexecute any aspects of the software components disclosed herein.According to various implementations of the concepts and technologiesdisclosed herein, the distributed computing environment 800 may providethe software functionality described herein as a service to the clientsusing devices 806. It should be understood that the devices 806 caninclude real or virtual machines including, but not limited to, servercomputers, web servers, personal computers, mobile computing devices,smart phones, and/or other devices, which can include user inputdevices. As such, various configurations of the concepts andtechnologies disclosed herein enable any device configured to access thedistributed computing environment 800 to utilize the functionalitydescribed herein for creating and supporting a access control policyblockchain ledger, among other aspects.

Turning now to FIG. 9, an illustrative computing device architecture 900for a computing device that is capable of executing various softwarecomponents is described herein for supporting a blockchain ledger andapplying access control policy to the blockchain ledger. The computingdevice architecture 900 is applicable to computing devices that canmanage a blockchain ledger. In some configurations, the computingdevices include, but are not limited to, mobile telephones, on-boardcomputers, tablet devices, slate devices, portable video game devices,traditional desktop computers, portable computers (e.g., laptops,notebooks, ultra-portables, and netbooks), server computers, gameconsoles, and other computer systems. The computing device architecture900 is applicable to the Certificate Authority 110, client/servers120A-C and blockchain platform 130 shown in FIG. 1 and computing device806A-N shown in FIG. 8.

The computing device architecture 900 illustrated in FIG. 9 includes aprocessor 902, memory components 904, network connectivity components906, sensor components 908, input/output components 910, and powercomponents 912. In the illustrated configuration, the processor 902 isin communication with the memory components 904, the networkconnectivity components 906, the sensor components 908, the input/output(“I/O”) components 910, and the power components 912. Although noconnections are shown between the individual components illustrated inFIG. 9, the components can interact to carry out device functions. Insome configurations, the components are arranged so as to communicatevia one or more busses (not shown).

The processor 902 includes a central processing unit (“CPU”) configuredto process data, execute computer-executable instructions of one or moreapplication programs, and communicate with other components of thecomputing device architecture 900 in order to perform variousfunctionality described herein. The processor 902 may be utilized toexecute aspects of the software components presented herein and,particularly, those that utilize, at least in part, secure data.

In some configurations, the processor 902 includes a graphics processingunit (“GPU”) configured to accelerate operations performed by the CPU,including, but not limited to, operations performed by executing securecomputing applications, general-purpose scientific and/or engineeringcomputing applications, as well as graphics-intensive computingapplications such as high resolution video (e.g., 620P, 1080P, andhigher resolution), video games, three-dimensional (“3D”) modelingapplications, and the like. In some configurations, the processor 902 isconfigured to communicate with a discrete GPU (not shown). In any case,the CPU and GPU may be configured in accordance with a co-processingCPU/GPU computing model, wherein a sequential part of an applicationexecutes on the CPU and a computationally-intensive part is acceleratedby the GPU.

In some configurations, the processor 902 is, or is included in, asystem-on-chip (“SoC”) along with one or more of the other componentsdescribed herein below. For example, the SoC may include the processor902, a GPU, one or more of the network connectivity components 906, andone or more of the sensor components 908. In some configurations, theprocessor 902 is fabricated, in part, utilizing a package-on-package(“PoP”) integrated circuit packaging technique. The processor 902 may bea single core or multi-core processor.

The processor 902 may be created in accordance with an ARM architecture,available for license from ARM HOLDINGS of Cambridge, United Kingdom.Alternatively, the processor 902 may be created in accordance with anx86 architecture, such as is available from INTEL CORPORATION ofMountain View, Calif. and others. In some configurations, the processor902 is a SNAPDRAGON SoC, available from QUALCOMM of San Diego, Calif., aTEGRA SoC, available from NVIDIA of Santa Clara, Calif., a HUMMINGBIRDSoC, available from SAMSUNG of Seoul, South Korea, an Open MultimediaApplication Platform (“OMAP”) SoC, available from TEXAS INSTRUMENTS ofDallas, Tex., a customized version of any of the above SoCs, or aproprietary SoC.

The memory components 904 include a random access memory (“RAM”) 914, aread-only memory (“ROM”) 916, an integrated storage memory (“integratedstorage”) 918, and a removable storage memory (“removable storage”) 920.In some configurations, the RAM 914 or a portion thereof, the ROM 916 ora portion thereof, and/or some combination of the RAM 914 and the ROM916 is integrated in the processor 902. In some configurations, the ROM916 is configured to store a firmware, an operating system or a portionthereof (e.g., operating system kernel), and/or a bootloader to load anoperating system kernel from the integrated storage 918 and/or theremovable storage 920.

The integrated storage 918 can include a solid-state memory, a harddisk, or a combination of solid-state memory and a hard disk. Theintegrated storage 918 may be soldered or otherwise connected to a logicboard upon which the processor 902 and other components described hereinalso may be connected. As such, the integrated storage 918 is integratedin the computing device. The integrated storage 918 is configured tostore an operating system or portions thereof, application programs,data, and other software components described herein.

The removable storage 920 can include a solid-state memory, a hard disk,or a combination of solid-state memory and a hard disk. In someconfigurations, the removable storage 920 is provided in lieu of theintegrated storage 918. In other configurations, the removable storage920 is provided as additional optional storage. In some configurations,the removable storage 920 is logically combined with the integratedstorage 918 such that the total available storage is made available as atotal combined storage capacity. In some configurations, the totalcombined capacity of the integrated storage 918 and the removablestorage 920 is shown to a user instead of separate storage capacitiesfor the integrated storage 918 and the removable storage 920.

The removable storage 920 is configured to be inserted into a removablestorage memory slot (not shown) or other mechanism by which theremovable storage 920 is inserted and secured to facilitate a connectionover which the removable storage 920 can communicate with othercomponents of the computing device, such as the processor 902. Theremovable storage 920 may be embodied in various memory card formatsincluding, but not limited to, PC card, CompactFlash card, memory stick,secure digital (“SD”), miniSD, microSD, universal integrated circuitcard (“UICC”) (e.g., a subscriber identity module (“SIM”) or universalSIM (“USIM”)), a proprietary format, or the like.

It can be understood that one or more of the memory components 904 canstore an operating system. According to various configurations, theoperating system may include, but is not limited to, server operatingsystems such as various forms of UNIX certified by The Open Group andLINUX certified by the Free Software Foundation, or aspects ofSoftware-as-a-Service (SaaS) architectures, such as MICROSFT AZURE fromMicrosoft Corporation of Redmond, Wash. or AWS from Amazon Corporationof Seattle, Wash. The operating system may also include WINDOWS MOBILEOS from Microsoft Corporation of Redmond, Wash., WINDOWS PHONE OS fromMicrosoft Corporation, WINDOWS from Microsoft Corporation, MAC OS or IOSfrom Apple Inc. of Cupertino, Calif., and ANDROID OS from Google Inc. ofMountain View, Calif. Other operating systems are contemplated.

The network connectivity components 906 include a wireless wide areanetwork component (“WWAN component”) 922, a wireless local area networkcomponent (“WLAN component”) 924, and a wireless personal area networkcomponent (“WPAN component”) 926. The network connectivity components906 facilitate communications to and from the network 956 or anothernetwork, which may be a WWAN, a WLAN, or a WPAN. Although only thenetwork 956 is illustrated, the network connectivity components 906 mayfacilitate simultaneous communication with multiple networks, includingthe network 956 of FIG. 9. For example, the network connectivitycomponents 906 may facilitate simultaneous communications with multiplenetworks via one or more of a WWAN, a WLAN, or a WPAN.

The network 956 may be or may include a WWAN, such as a mobiletelecommunications network utilizing one or more mobiletelecommunications technologies to provide voice and/or data services toa computing device utilizing the computing device architecture 900 viathe WWAN component 922. The mobile telecommunications technologies caninclude, but are not limited to, Global System for Mobile communications(“GSM”), Code Division Multiple Access (“CDMA”) ONE, CDMA7000, UniversalMobile Telecommunications System (“UMTS”), Long Term Evolution (“LTE”),and Worldwide Interoperability for Microwave Access (“WiMAX”). Moreover,the network 956 may utilize various channel access methods (which may ormay not be used by the aforementioned standards) including, but notlimited to, Time Division Multiple Access (“TDMA”), Frequency DivisionMultiple Access (“FDMA”), CDMA, wideband CDMA (“W-CDMA”), OrthogonalFrequency Division Multiplexing (“OFDM”), Space Division Multiple Access(“SDMA”), and the like. Data communications may be provided usingGeneral Packet Radio Service (“GPRS”), Enhanced Data rates for GlobalEvolution (“EDGE”), the High-Speed Packet Access (“HSPA”) protocolfamily including High-Speed Downlink Packet Access (“HSDPA”), EnhancedUplink (“EUL”) or otherwise termed High-Speed Uplink Packet Access(“HSUPA”), Evolved HSPA (“HSPA+”), LTE, and various other current andfuture wireless data access standards. The network 956 may be configuredto provide voice and/or data communications with any combination of theabove technologies. The network 956 may be configured to or be adaptedto provide voice and/or data communications in accordance with futuregeneration technologies.

In some configurations, the WWAN component 922 is configured to providedual-multi-mode connectivity to the network 956. For example, the WWANcomponent 922 may be configured to provide connectivity to the network956, wherein the network 956 provides service via GSM and UMTStechnologies, or via some other combination of technologies.Alternatively, multiple WWAN components 922 may be utilized to performsuch functionality, and/or provide additional functionality to supportother non-compatible technologies (i.e., incapable of being supported bya single WWAN component). The WWAN component 922 may facilitate similarconnectivity to multiple networks (e.g., a UMTS network and an LTEnetwork).

The network 956 may be a WLAN operating in accordance with one or moreInstitute of Electrical and Electronic Engineers (“IEEE”) 802.11standards, such as IEEE 802.11a, 802.11b, 802.11g, 802.11n, and/orfuture 802.11 standard (referred to herein collectively as WI-FI). Draft802.11 standards are also contemplated. In some configurations, the WLANis implemented utilizing one or more wireless WI-FI access points. Insome configurations, one or more of the wireless WI-FI access points areanother computing device with connectivity to a WWAN that arefunctioning as a WI-FI hotspot. The WLAN component 924 is configured toconnect to the network 956 via the WI-FI access points. Such connectionsmay be secured via various encryption technologies including, but notlimited to, WI-FI Protected Access (“WPA”), WPA2, Wired EquivalentPrivacy (“WEP”), and the like.

The network 956 may be a WPAN operating in accordance with Infrared DataAssociation (“IrDA”), BLUETOOTH, wireless Universal Serial Bus (“USB”),Z-Wave, ZIGBEE, or some other short-range wireless technology. In someconfigurations, the WPAN component 926 is configured to facilitatecommunications with other devices, such as peripherals, computers, orother computing devices via the WPAN.

The sensor components 908 include a magnetometer 928, an ambient lightsensor 930, a proximity sensor 932, an accelerometer 934, a gyroscope936, and a Global Positioning System sensor (“GPS sensor”) 938. It iscontemplated that other sensors, such as, but not limited to,temperature sensors or shock detection sensors, also may be incorporatedin the computing device architecture 900.

The I/O components 910 include a display 940, a touchscreen 942, a dataI/O interface component (“data I/O”) 944, an audio I/O interfacecomponent (“audio I/O”) 946, a video I/O interface component (“videoI/O”) 948, and a camera 950. In some configurations, the display 940 andthe touchscreen 942 are combined. In some configurations two or more ofthe data I/O component 944, the audio I/O component 946, and the videoI/O component 948 are combined. The I/O components 910 may includediscrete processors configured to support the various interfacesdescribed below or may include processing functionality built-in to theprocessor 902.

The illustrated power components 912 include one or more batteries 952,which can be connected to a battery gauge 954. The batteries 952 may berechargeable or disposable. Rechargeable battery types include, but arenot limited to, lithium polymer, lithium ion, nickel cadmium, and nickelmetal hydride. Each of the batteries 952 may be made of one or morecells.

The power components 912 may also include a power connector, which maybe combined with one or more of the aforementioned I/O components 910.The power components 912 may interface with an external power system orcharging equipment via an I/O component.

EXAMPLES OF VARIOUS IMPLEMENTATIONS

In closing, although the various configurations have been described inlanguage specific to structural features and/or methodological acts, itis to be understood that the subject matter defined in the appendedrepresentations is not necessarily limited to the specific features oracts described. Rather, the specific features and acts are disclosed asexample forms of implementing the claimed subject matter.

The present disclosure is made in light of the following clauses:

Clause 1: A computer-implemented method for system level function basedaccess control for smart contract execution on a blockchain, the methodcomprising, in a kernel execution framework for smart contract executionon a blockchain, where the kernel execution framework is configured toperform function boundary detection: detecting a function call by one ormore methods of a smart contract on the blockchain; adding the functioncall to a function call stack for the smart contract; checking thefunction call stack against a set of function based access control rulesthat defines one or more permitted or prohibited sequences of functioncalls; and if the function call stack includes one or more functioncalls that are not permitted under the set of function based accesscontrol rules, then blocking execution or completion of the functioncall.

Clause 2. The computer-implemented method of Clause 1, where: thefunction call stack includes each function called during execution ofthe smart contract; the set of function based access control rulesincludes at least one access control rule that defines a sequence offunction calls; and the step of checking the function call stack againstthe set of function based access control rules includes checking thefunction call stack against the sequence of function calls defined inthe access control rule that defines a sequence of function calls.

Clause 3. The computer-implemented method of Clause 1, where: the stepof defining a set of function based access control rules includes atleast one data based access control rule; the step of detecting afunction call by one or more methods of a smart contract on theblockchain includes detecting at least one value included in thefunction call stack; the step of checking the function call stackagainst a set of function based access control rules includes checkingthe at least one value included in the function call stack against thedata based access control rule; and the step of, if the sequence offunction calls is not permitted under the set of function based accesscontrol rules, then blocking the function call, includes: if the atleast one value included in the sequence of function calls is notpermitted under the set of data based access control rules, thenblocking the function call.

Clause 4. The computer-implemented method of Clause 1, where: the set offunction based access control rules is stored on a blockchain; and themethod includes modifying the set of function based access control rulesby adding a function based access control rule block to the blockchain.

Clause 5. The computer-implemented method of Clause 1, wherein thekernel execution framework comprises a Linux operating system frameworkand the function boundary detection comprises extended Berkeley PacketFiltering.

Clause 6. The computer-implemented method of Clause 1, where the stepsof detecting a function call by one or more methods of a smart contracton the blockchain, adding the function call to a function call stack forthe smart contract, checking the function call stack against the set offunction based access control rules, and, if the function call is notpermitted under the set of function based access control rules, thenblocking the function call are performed within one or more virtualmachines executing the framework for execution of the smart contract onthe blockchain.

Clause 7. The computer-implemented method of Clause 1, where the set offunction based access control rules includes at least one of a whitelist of allowed sequences of function calls and a black list ofprohibited sequences of function calls.

Clause 8. A system for system level function based access control forsmart contract execution on a blockchain, the system comprising: one ormore processors; and one or more memory devices in communication withthe one or more processors, the memory devices having computer-readableinstructions stored thereupon that, when executed by the processors,cause the processors to perform a method for system level function basedaccess control for smart contract execution on a blockchain, the methodcomprising, in a kernel execution framework for smart contract executionon a blockchain, where the kernel execution framework is configured toperform function boundary detection: detecting a function call by one ormore methods of a smart contract on the blockchain; adding the functioncall to a function call stack for the smart contract; checking thefunction call stack against a set of function based access control rulesthat defines one or more permitted or prohibited sequences of functioncalls; and if the function call stack includes one or more functioncalls that are not permitted under the set of function based accesscontrol rules, then blocking execution or completion of the functioncall.

Clause 9. The system of Clause 8, where: the function call stackincludes each function called during execution of the smart contract;the set of function based access control rules includes at least oneaccess control rule that defines a sequence of function calls; and thestep of checking the function call stack against the set of functionbased access control rules includes checking the function call stackagainst the sequence of function calls defined in the access controlrule that defines a sequence of function calls.

Clause 10. The system of Clause 8, where: the step of defining a set offunction based access control rules includes at least one data basedaccess control rule; the step of detecting a function call between oneor more methods of a smart contract on the blockchain includes detectingat least one value included in the function call stack; the step ofchecking the function call stack against the set of function basedaccess control rules includes checking the at least one value includedin the function call stack against the data based access control rule;and the step of, if the sequence of function calls is not permittedunder the set of function based access control rules, then blocking thefunction call, includes: if the at least one value included in thesequence of function calls is not permitted under the set of data basedaccess control rules, then blocking the function call.

Clause 11. The system of Clause 8, where: the set of function basedaccess control rules is stored on a blockchain; and the method includesmodifying the set of function based access control rules by adding afunction based access control rule block to the blockchain.

Clause 12. The system of Clause 8, wherein the kernel executionframework comprises a Linux operating system framework and the functionboundary detection comprises extended Berkeley Packet Filtering.

Clause 13. The system of Clause 8, where the steps of detecting afunction call by one or more methods of a smart contract on theblockchain, adding the function call to a function call stack for thesmart contract, checking the function call stack against the set offunction based access control rules, and, if the function call is notpermitted under the set of function based access control rules, thenblocking the function call are performed within one or more virtualmachines executing the framework for execution of the smart contract onthe blockchain.

Clause 14. The system of Clause 8, where the set of function basedaccess control rules includes at least one of a white list of allowedsequences of function calls and a black list of prohibited sequences offunction calls.

Clause 15. One or more computer storage media having computer executableinstructions stored thereon which, when executed by one or moreprocessors, cause the processors to execute a method for system levelfunction based access control for smart contract execution on ablockchain, the method comprising, in a kernel execution framework forsmart contract execution on a blockchain, where the kernel executionframework is configured to perform function boundary detection:detecting a function call by one or more methods of a smart contract onthe blockchain; adding the function call to a function call stack forthe smart contract; checking the function call stack against a set offunction based access control rules that defines one or more permittedor prohibited sequences of function calls; and if the function callstack includes one or more function calls that are not permitted underthe set of function based access control rules, then blocking executionor completion of the function call.

Clause 16. The computer storage media of Clause 15, where: the functioncall stack includes each function called during execution of the smartcontract; the set of function based access control rules includes atleast one access control rule that defines a sequence of function calls;and the step of checking the function call stack against the set offunction based access control rules includes checking the function callstack against the sequence of function calls defined in the accesscontrol rule that defines a sequence of function calls.

Clause 17. The computer storage media of Clause 15, where: the step ofdefining a set of function based access control rules includes at leastone data based access control rule; the step of detecting a functioncall between one or more methods of a smart contract on the blockchainincludes detecting at least one value included in the function callstack; the step of checking the function call stack against the set offunction based access control rules includes checking the at least onevalue included in the function call stack against the data based accesscontrol rule; and the step of, if the sequence of function calls is notpermitted under the set of function based access control rules, thenblocking the function call, includes: if the at least one value includedin the sequence of function calls is not permitted under the set of databased access control rules, then blocking the function call.

Clause 18. The computer storage media of Clause 15, where: the set offunction based access control rules is stored on a blockchain; and themethod includes modifying the set of function based access control rulesby adding a function based access control rule block to the blockchain.

Clause 19. The computer storage media of Clause 15, wherein the kernelexecution framework comprises a Linux operating system framework and thefunction boundary detection comprises extended Berkeley PacketFiltering.

Clause 20. The computer storage media of Clause 15, where the steps ofdetecting a function call by one or more methods of a smart contract onthe blockchain, adding the function call to a function call stack forthe smart contract, checking the function call stack against the set offunction based access control rules, and, if the function call is notpermitted under the set of function based access control rules, thenblocking the function call are performed within one or more virtualmachines executing the framework for execution of the smart contract onthe blockchain.

Although the subject matter presented herein has been described inlanguage specific to computer structural features, methodological andtransformative acts, specific computing machinery, and computer readablemedia, it is to be understood that the subject matter set forth in theappended claims is not necessarily limited to the specific features,acts, or media described herein. Rather, the specific features, acts andmediums are disclosed as example forms of implementing the claimedsubject matter.

The subject matter described above is provided by way of illustrationonly and should not be construed as limiting. Various modifications andchanges can be made to the subject matter described herein withoutfollowing the example configurations and applications illustrated anddescribed, and without departing from the scope of the presentdisclosure, which is set forth in the following claims.

What is claimed is:
 1. A computer-implemented method for system levelfunction based access control for smart contract execution on ablockchain, the method comprising, in a kernel execution framework forsmart contract execution on a blockchain, where the kernel executionframework is configured to perform function boundary detection:detecting a function call by one or more methods of a smart contract onthe blockchain; adding the function call to a function call stack forthe smart contract; checking the function call stack against a set offunction based access control rules that defines one or more permittedor prohibited sequences of function calls; and if the function callstack includes one or more function calls that are not permitted underthe set of function based access control rules, then blocking executionor completion of the function call.
 2. The computer-implemented methodof claim 1, where: the function call stack includes each function calledduring execution of the smart contract; the set of function based accesscontrol rules includes at least one access control rule that defines asequence of function calls; and the step of checking the function callstack against the set of function based access control rules includeschecking the function call stack against the sequence of function callsdefined in the access control rule that defines a sequence of functioncalls.
 3. The computer-implemented method of claim 1, where: the step ofdefining a set of function based access control rules includes at leastone data based access control rule; the step of detecting a functioncall by one or more methods of a smart contract on the blockchainincludes detecting at least one value included in the function callstack; the step of checking the function call stack against a set offunction based access control rules includes checking the at least onevalue included in the function call stack against the data based accesscontrol rule; and the step of, if the sequence of function calls is notpermitted under the set of function based access control rules, thenblocking the function call, includes: if the at least one value includedin the sequence of function calls is not permitted under the set of databased access control rules, then blocking the function call.
 4. Thecomputer-implemented method of claim 1, where: the set of function basedaccess control rules is stored on a blockchain; and the method includesmodifying the set of function based access control rules by adding afunction based access control rule block to the blockchain.
 5. Thecomputer-implemented method of claim 1, wherein the kernel executionframework comprises a Linux operating system framework and the functionboundary detection comprises extended Berkeley Packet Filtering.
 6. Thecomputer-implemented method of claim 1, where the steps of detecting afunction call by one or more methods of a smart contract on theblockchain, adding the function call to a function call stack for thesmart contract, checking the function call stack against the set offunction based access control rules, and, if the function call is notpermitted under the set of function based access control rules, thenblocking the function call are performed within one or more virtualmachines executing the framework for execution of the smart contract onthe blockchain.
 7. The computer-implemented method of claim 1, where theset of function based access control rules includes at least one of awhite list of allowed sequences of function calls and a black list ofprohibited sequences of function calls.
 8. A system for system levelfunction based access control for smart contract execution on ablockchain, the system comprising: one or more processors; and one ormore memory devices in communication with the one or more processors,the memory devices having computer-readable instructions storedthereupon that, when executed by the processors, cause the processors toperform a method for system level function based access control forsmart contract execution on a blockchain, the method comprising, in akernel execution framework for smart contract execution on a blockchain,where the kernel execution framework is configured to perform functionboundary detection: detecting a function call by one or more methods ofa smart contract on the blockchain; adding the function call to afunction call stack for the smart contract; checking the function callstack against a set of function based access control rules that definesone or more permitted or prohibited sequences of function calls; and ifthe function call stack includes one or more function calls that are notpermitted under the set of function based access control rules, thenblocking execution or completion of the function call.
 9. The system ofclaim 8, where: the function call stack includes each function calledduring execution of the smart contract; the set of function based accesscontrol rules includes at least one access control rule that defines asequence of function calls; and the step of checking the function callstack against the set of function based access control rules includeschecking the function call stack against the sequence of function callsdefined in the access control rule that defines a sequence of functioncalls.
 10. The system of claim 8, where: the step of defining a set offunction based access control rules includes at least one data basedaccess control rule; the step of detecting a function call between oneor more methods of a smart contract on the blockchain includes detectingat least one value included in the function call stack; the step ofchecking the function call stack against the set of function basedaccess control rules includes checking the at least one value includedin the function call stack against the data based access control rule;and the step of, if the sequence of function calls is not permittedunder the set of function based access control rules, then blocking thefunction call, includes: if the at least one value included in thesequence of function calls is not permitted under the set of data basedaccess control rules, then blocking the function call.
 11. The system ofclaim 8, where: the set of function based access control rules is storedon a blockchain; and the method includes modifying the set of functionbased access control rules by adding a function based access controlrule block to the blockchain.
 12. The system of claim 8, wherein thekernel execution framework comprises a Linux operating system frameworkand the function boundary detection comprises extended Berkeley PacketFiltering.
 13. The system of claim 8, where the steps of detecting afunction call by one or more methods of a smart contract on theblockchain, adding the function call to a function call stack for thesmart contract, checking the function call stack against the set offunction based access control rules, and, if the function call is notpermitted under the set of function based access control rules, thenblocking the function call are performed within one or more virtualmachines executing the framework for execution of the smart contract onthe blockchain.
 14. The system of claim 8, where the set of functionbased access control rules includes at least one of a white list ofallowed sequences of function calls and a black list of prohibitedsequences of function calls.
 15. One or more computer storage mediahaving computer executable instructions stored thereon which, whenexecuted by one or more processors, cause the processors to execute amethod for system level function based access control for smart contractexecution on a blockchain, the method comprising, in a kernel executionframework for smart contract execution on a blockchain, where the kernelexecution framework is configured to perform function boundarydetection: detecting a function call by one or more methods of a smartcontract on the blockchain; adding the function call to a function callstack for the smart contract; checking the function call stack against aset of function based access control rules that defines one or morepermitted or prohibited sequences of function calls; and if the functioncall stack includes one or more function calls that are not permittedunder the set of function based access control rules, then blockingexecution or completion of the function call.
 16. The computer storagemedia of claim 15, where: the function call stack includes each functioncalled during execution of the smart contract; the set of function basedaccess control rules includes at least one access control rule thatdefines a sequence of function calls; and the step of checking thefunction call stack against the set of function based access controlrules includes checking the function call stack against the sequence offunction calls defined in the access control rule that defines asequence of function calls.
 17. The computer storage media of claim 15,where: the step of defining a set of function based access control rulesincludes at least one data based access control rule; the step ofdetecting a function call between one or more methods of a smartcontract on the blockchain includes detecting at least one valueincluded in the function call stack; the step of checking the functioncall stack against the set of function based access control rulesincludes checking the at least one value included in the function callstack against the data based access control rule; and the step of, ifthe sequence of function calls is not permitted under the set offunction based access control rules, then blocking the function call,includes: if the at least one value included in the sequence of functioncalls is not permitted under the set of data based access control rules,then blocking the function call.
 18. The computer storage media of claim15, where: the set of function based access control rules is stored on ablockchain; and the method includes modifying the set of function basedaccess control rules by adding a function based access control ruleblock to the blockchain.
 19. The computer storage media of claim 15,wherein the kernel execution framework comprises a Linux operatingsystem framework and the function boundary detection comprises extendedBerkeley Packet Filtering.
 20. The computer storage media of claim 15,where the steps of detecting a function call by one or more methods of asmart contract on the blockchain, adding the function call to a functioncall stack for the smart contract, checking the function call stackagainst the set of function based access control rules, and, if thefunction call is not permitted under the set of function based accesscontrol rules, then blocking the function call are performed within oneor more virtual machines executing the framework for execution of thesmart contract on the blockchain.